The proposed studies include an examination of tissues and organs from rabbits which have been receiving topical drops of marihuana derivatives in their eyes twice daily over a twelve month period. The tissue examination will consist of organ weights relative to those in the literature for rabbits of similar size, and also, specifically, organs which have been found in other studies to be changed by marihuana administration. Further pharmacological testing will be made to determine the effect of Delta 9-tetrahydrocannabinol on blood flow through ocular tissues to identify the specific locus of action in the eye. In addition, other naturally occurring marihuana derivatives will be tested for their efficacy in reducing intraocular pressure. The interactions between Delta 9-tetrahydrocannabinol and other drugs will be investigated as regards their effects on the eye with specific reference to intraocular pressure and total outflow facility. BIBLIOGRAPHIC REFERENCES: Green, K. and Kim, K. 1977. Papaverine and verapamil interaction with prostaglandin E2 and Delta 9-tetrahydrocannabinol in the eye. Exp. Eye Res. 24, in press. Green, K. and Kim, K. 1977. Acute dose response of intraocular pressure to topical and oral cannabinoids. Proc. Soc. Exp. Biol. Med. 154, in press.